linux-kernel - Re: [PATCH] include/linux/slab.h: new KFREE() macro.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <200701100243.l0A2hZxH013254@turing-police.cc.vt.edu>
Date:	Tue, 09 Jan 2007 21:43:35 -0500
From:	Valdis.Kletnieks@...edu
To:	Amit Choudhary <amit2030@...oo.com>
Cc:	Pekka Enberg <penberg@...helsinki.fi>,
	Hua Zhong <hzhong@...il.com>,
	Christoph Hellwig <hch@...radead.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] include/linux/slab.h: new KFREE() macro.

On Tue, 09 Jan 2007 16:00:51 PST, Amit Choudhary said:

> What did you understand when I wrote that "if you access the same memory again using the variable
> 'x"?
> 
> Using variable 'x' means using variable 'x' and not variable 'y'.

Right - but in real-world code, 'y' is the actual problem.

> Did I ever say that it fixes that kind of bug?

The point you're missing is that you're "fixing" a failure mode that in
general isn't seen, and ignoring the failure mode that *is* seen.

> Dereferencing 'x' means dereferencing 'x' and not dereferencing 'y'.

And neither "x" nor "y" is "the set of all still-live pointers to already-freed
memory" - which is why your proposal doesn't actually do anything effective.

Content of type "application/pgp-signature" skipped